6 Stop ND

J

jpwild

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I have a B+W 6 stop ND filter, and would like to know the calculation to get correct exposure from metering the subject and getting the shutterspeed whilst the ND is off then lens.

I don't have access to the Iphone app for this, so will have to learn it, but I'm just not sure what the actual calculation is.

Thanks.

I also have a 450D camera - which metering mode is best suited to use with this filter.This will be for landscapes / sky use.

Thanks for help
 
Well, there's no magic formula really just work it out one stop at a time.

Working with shutter speeds, if you metered without the filter at 1/1000 at a given aperture:

1/1000
1/500 - 1 Stop
1/250 - 2 Stops
1/125 - 3 Stops
1/60 - 4 Stops
1/30 - 5 Stops
1/15 - 6 Stops

Working with apertures, if you metered without the filter at f/16 at a given shutter speed:


f/16
f/11 - 1 Stop
f/8 - 2 Stops
f/5.6 - 3 Stops
f/4 - 4 Stops
f/2.8 - 5 Stops
f/1.8 - 6 Stops
 
A six stop is used mainly to cut out the light so you get a slow shutter speed to blur water movement.

Also if using a modern camera with through the lens metering ,the camera will work out the right exposure if in auto--aperture priority--or shutter priority. just check the screen to make sure.
 
Meter normally, then count back the shutter speed as MrT says and fit the filter. Remember to cover the viewfinder as light leaks in there during long exposures in bright light. Set long exposure noise reduction, which will lock up the camera for the same time as the shutter speed - just in case you wonder what the camera is up to.

That should be it. However, you might well need to tweak the exposure so check the LCD/histogram as you would normally.

Six stops is not so dark that you can't meter with the filter on in bright light. Might be worth a try, but also make sure there is absolutely no light creeeping in through the viewinder during metering - press your eye tight up against it or the reading could be miles out.
 
The aperture is still relevant as to what you wish to achieve and what you are photographing. Using F1.8 for a landscape shot where you want to blur water and/or cloud motion probably wouldn't work as you don't really use such wide apertures for landscape. Therefore, F8 or smaller would still work but mean a longer shutter speed.

6 stop and above filters are quite specialist so you'll find them mostly at ise for long daytime exposures.
 
Scarecrow said:
Actually, with the apertures, you would need to go the other way - f/16 to f/1.8 - to let in enough light when using the filter.
Click to expand...

Oops, yeah you're absolutely right. I butchered these from a table I did a while ago. I will fix that now. To be honest the aperture scale is essentially useless since it's highly unlikely you'd want to have the aperture as the variable.
 
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